[PyQt] Resize button with window resize

[Alfalfa]

You have to set the vertical policy for your button (either as minimum or expanding):

        sizePolicy = QSizePolicy(QSizePolicy.Minimum, QSizePolicy.Minimum)
        self.quitButton.setSizePolicy(sizePolicy)

When you want to change the layout but don't know where to start, a trick is to mess in QtDesigner until you find the right setting. Then save the ui file, convert it to python and see how it is done :)

As for the constructive critisism, you should avoid wildcard in imports as it is considered bad practice:

from PyQt5.QtWidgets import *

And always use explicit inheritances, such as:

        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Minimum)

It makes it clear on which module your application rely, and avoid name collision.